Resettable glow switch starter for electric discharge devices



Marh 29,1966 L. w. COOK 3,243,549

RESETTABLE GLOW SWITCH STARTER FOR ELECTRIC DISCHARGE DEVICES Fig. l'. 3

Filed Jan. 15, 1964 Inventofi Leona rd W. Cook b3 Wadi/$411M His Attorney United States Patent 3,243,549 RESE'ITABLE GLOW SWITCH STARTER FOR ELECTRIC DISCHARGE DEVICES Leonard W. Cook, Warwick, R.I., assignor to General Electric Company, a corporation of New York Filed Jan. 15, 1964, Ser. No. 337,758 3 Claims. (Cl. ZOO-113.5)

My invention relates to starters for electric discharge devices and more particularly to resettable starters which prevent blinking during attempts to start such devices.

It is customary today to prevent blinking during the starting of discharge devices by utilizing a manually resettable thermoswitch connected in series with the glow switch to interrupt the circuit after repeated futile attempts to start a defective lamp. The thermoswitch usually employs a bimetal which is deflected by heat from an auxiliary resistor also in series with the glow switch. Each attempt to start the discharge device increases the heat "output of the resistor until eventually the bimetal deflects sufliciently to interrupt the glow switch circuit. It has been found unsatisfactory, however, to use .a series resistor as a heat source for the reason that the resistor heat is dependent on the current through the resistor, which is in turn subject to the inherent variations in source voltage, impedance of the ballast circuit, and the cycling pattern of the glow switch. Because of the many variables external to the starter which affect its performance, it has always been necessary to impose rigid tolerances on the operation of the heater-interrupter mechanism. These tolerances have made it impractical to completely eliminate hand adjusting operations in the starter assembly.

My invention circumvents these problems by utilizing the heat generated within a glow switch having a metallic housing to directly influence the bimetal, thus eliminating the eifect of all variables external to the starter. With my invention broader operating tolerances in the glow switch construction can be accepted and individual hand calibrations can be eliminated.

It is an object of this invention to provide an improved arrangement for preventing blinking during attempted starting operations on the electric discharge devices.

It is another object of my invention to provide an electric discharge device starter with an improved mechanism for preventing blinking whose operation is not subject to variations in supply current.

It is a further object of myinvention to provide an improved starter with a thermoswitch circuit interrupter which is actuated solely by the heat generated within the glow switch.

It is still another object of my invention to provide an improved starter for electric discharge devices which is more economical to produce and easier to assemble than present starters.

Further objects and advantages of my invention will become apparent as the following description proceeds. The features of novelty which characterize my invention will be pointed out with particularity in the claims anneXed to and forming a part of this specification.

In carrying out the objects of my invention, in one form thereof, the starter embodying my invention is located in the conventinal manner in a circuit in parallel with a gaseous electric discharge device. My starter incorporates an insulating plate which supports on one side a glow switch of the type having a metallic housing. A thermoswitch interrupter is mounted on the other side of the plate opposite the glow switch. An aperture in the plate between the glow switch and the thermally sensitive constituent of the thermoswitch interrupter permits a direct transfer of heat from the glow switch housing to the thermally sensitive member. Repeated futile attempts to start a defective discharge device result in an accumulation of heat within the glow switch housing. This build-up of heat is sensed by the thermoswitch which then functions to interrupt the glow switch circuit and thereby preclude damaging of the circuit components by further attempts to start the device. The starter is provided with a manual reset button which, when depressed, re-establishes the engagement of the contacts of the thermoswitch interrupter.

For a better understanding of my invention, reference may be made to the accompanying drawings in which:

FIGURE 1 is a view, partly in section, of the starter.

FIGURE 2 is a side view of the starter with the protective cap and reset button removed.

FIGURE 3 is a top view of the starter with the protective cap and reset button removed.

FIGURE 4 is an exploded view of the starter with the protective cap and reset button removed.

By reference to the drawings, particularly FIGURE 1, it will be seen that the operating components of the starter are housed in a metallic cap 1 lined with an insulating liner 2. The open end of the cap 1 is closed by a support means such as a circular insulating base disk 3 having spaced notches 4 cut in the periphery of the disk 3 which receive conventional securing tabs (not shown) forming a part of the cap 1. A pair of terminals 5 for the starter are mounted in and project through the base disk 3.

A generally rectangular insulating supporting plate 6 is mounted upright upon the base disk 3 by a pair of electrically conductive right-angle brackets 7, the respective leg 8 of each bracket against the base disk 3 being connected to one of the starter terminals 5. The bracket legs 9 contacting the plate 6 are secured thereto by means of terminal eyelets 10 and 11 penetrating the plate 6.

A glow switch 12 of the type described and claimed in my Patent No. 3,098,137 is mounted upon the insulating plate 6. The glow switch 12 has a metal housing with a first or cylindrical portion 13 and a second or flared base portion 14. A terminal lead 15 of the glow switch 12 is secured in the eyelet 10 in the insulating plate 6. In a glow switch of this type, having a metallic housing, the housing itself constitutes the second electrical terminal of the switch, Referring to FIGURES l and 2, it will be seen that a sector of the flared base portion 14 of the glow switch 12 projects through a transversely widened section 16 of an inverted T-shaped aperture 17 incised in the insulating plate 6. When the glow switch 12 is mounted in place upon the insulating plate 6, the cylindrical portion 13 lies juxtaposed an elongated portion 18 of the aperture 17, the aperture providing a pathway for radiant heat transmission from the glow switch 12 through the insulating plate.

In order to provide a means for interrupting the circuit of the glow switch after repeated abortive attempts to start a defective device, the starter includes a thermoswitch interrupter in series with the glow switch. The contact members of the thermoswitch comprise a thermally sensitive member, shown as a bimetallic strip 19 in the disclosed embodiment of my invention, and a cooperating resilient conductor 21.

The thermally sensitive member has an end portion 20 which is welded or otherwise conventionally aflixed to the sector of the flared base portion 14 of the glow switch 12 which projects through widened. section 16 of aperture 17. This thermally and electrically conductive connection places the strip 19 in a direct heat transfer relationship with the housing of the glow switch 12 and thus enables the strip 19 to accurately and quickly sense an accumulation of heat therein.

The resilient conductor 21 forming a part of the thermoswitch interrupter is connected to terminal eyelet 11 in the insulating plate 6 and is constrained in notches 22 and 23 in the uppermost edge of the plate 6. When the thermoswitch is closed, conductor 21 is deformed against its natural bias with a latching contact portion 24 of the conductor 21 engaging a latch dog 25 on bimetallic strip 19.

In order that the starter may be reset after it has functioned to interrupt the glow switch circuit, a manual reset arrangement is provided. A reset button 29 projects loosely through and is guided in an aperture 26 in a well 27 in the top of the protective cap 1 for the starter. The reset button 29 rests upon a U-shaped bend 28 in the conductor 21. One leg of the U-shaped bend 28 extends through notch 23 which serves as a support and a guide for the conductor 21. After an interruption of the glow switch circuit by the thermoswitch, the conductor 21 rests in an unbiased state out of engagement with the latch dog 25 of the bimetallic strip 19. To reestablish the engagement between the strip 19 and the conductor 21, the reset button 29, which is supported by the U-shaped bend 28 of the conductor 21, is manually depressed. Depressing the reset button 29 deflects the conductor 21 against its natural bias, bringing latch contact portion 24 of the conductor 21 into engagement with latch dog 25 of the strip 19.

A detailed explanation of tthe mode of operation of my starter will now be given. As is characteristic of any glow switch, each energization generates an increment of heat within the glow switch housing. When a glow switch is located in a conventional manner in the starting circuit of a gaseous electric discharge device, repeated abortive attempts to start the discharge device will result in an accumulation of heat within the glow switch housing even though some heat will, of course, be dissipated through the housing into the atmosphere. In my invention the metal housing of the glow switch 12 is mounted in physical contact with the bimetallic strip 19, and a major part of this accumulation of heat within the glow switch housing is transmitted to the strip 19. The bimetallic strip 19 is selected with characteristics such that within a predetermined temperature range the strip 19 will deflect from its ambient position sufficiently to release the latching contact portion 24 of the resilient conductor. The resiliency of the conductor 21 causes it to spring upwardly out of engagement with the conductor 21. This disengagement of the bimetallic strip 19 and the resilient conductor 21 interrupts the glow switch circuit, thus precluding any possibility of damaging the glow switch or other circuit components by further attempts to start the discharge device. After the defective discharge device has been replaced or repaired the starter must be manually reset, viz., the glow switch circuit must be closed by bringing the latching contact portion 24 of the conductor 21 again into engagement with the latch dog 25 of bimetallic strip 19. This is accomplished by manually depressing the reset button 29, which contacts the U-shaped bend 28 in conductor 21, against the resilient bias of the conductor 21 sufficiently to re-establish the engagement between latch dog 25 and conductor 21.

My invention is not limited to the particular details of construction of the embodiment illustrated and I contemplate that various and other modifications and applications will occur to those skilled in the art. It is therefore my intention that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of my invention.

4 What I claim as new and desire to Patent of the Unite-d States is:

1. A starter for a gaseous electric discharge device comprising:

(a) support means,

(b) an insulating plate mounted on said support means,

said insulating plate having an aperture formed therethrough,

(c) a glow switch having a thermally conductive housing including first and second portions, said glow switch being mounted on a first side of said insulating plate so that said first portion lies juxtaposed said aperture and said second portion extends through said aperture,

(d) electrically conductive, thermally sensitive means disposed on a second side of said insulating plate having an end portion mounted to said sec-0nd housing portion in direct electrical and thermal conductive contact therewith, and

(e) means mounted on said insulating plate for coopcrating with said electrically conductive, thermally sensitive means to interrupt conduction of said glow switch and to preclude re-energization of the electric discharge device after actuation of said electrically conductive, thermally sensitive means by the heat from said glow switch.

2. A starter for a gaseous electric discharge device comprising:

(a) support means,

(b) an insulating plate mounted on said support means, said insulating plate having a T-shape-d aperture formed therethrough,

(c) a glow switch having a thermally conductive housing including first and second portions, said glow switch being mounted on a first side of said insulating plate so that said first portion lies juxtaposed said aperture and said second portion extends through said aperture, said second portion of said housing having a flared base portion formed thereon,

(d) electrically conductive, thermally sensitive means disposed on a second side of said insulating plate having an end portion mounted to said flared portion in direct electrical and thermal conductive contact therewifli, .a direct radiant heat transmission relationship existing between said first portion of said housing and a substantial length of said electrically conductive, thermally sensitive means, and

i (e) means mounted on said insulating plate for cooperating with said electrically conductive, thermally sensitive means to interrupt conduction of said glow switch and to preclude re-energization of the electric discharge device after actuation of said electrically conductive, thermally sensitive means by the heat from said glow switch.

3. For use with a gaseous electric discharge device, a

starter comprising:

(a) support means,

(b) a glow switch having a metallic housing constituting one electrical terminal of the switch and adapted to mounted on said support means,

(c) a bimetallic strip located in the circuit of said glow switch for actuation by heat from said glow switch, said strip having a latched dog projecting from its free end,

(d) an insulating plate mounted on said support means supporting said glow switch on one side, said himetallic strip being disposed -on the other side of said plate, said plate having a T-shaped aperture between said glow switch and said strip, said aperture permitting mounting of said strip to said housing in a. direct thermal and electrical connection therewith and permitting direct radiant heat transmission between said glow switch housing and a. substantial length of said bimetallic strip,

secure by Letters 3,243,549 5 6 (e) a resilient electrical conductor mounted on said References Cited by the Examiner insulating plate and engageable with said bimetallic UNITED STATES PATENTS strip, said conductor being biased toward a circuit intern} {H h b t f 2,293,897 8/1942 Gl'ef 200-113-5 P 1 g P cm Y, 9 ac Sal 3,098,137 7/1963 000k zoo-113.5 strip by the heat of sand glow switch, said conductor 5 3,161,746 12/1964 cook et a1 200 113.5

will be released by said strip, and (f) a manual reset button for moving said conductor BERNARD A. GILHEANY, Primary Examiner.

into re-engagement with said latched dog. L. WRIGHT Assistant Examiner 

1. A STARTER FOR A GASEOUS ELECTRIC DISCHARGE DEVICE COMPRISING: (A) SUPPORT MEANS, (B) AN INSULATING PLATE MOUNTED ON SAID SUPPORT MEANS, SAID INSULATING PLATE HAVING AN APERTURE FORMED THERETHROUGH, (C) A GLOW SWITCH HAVING A THERMALLY CONDUCTIVE HOUSING INCLUDING FIRST AND SECOND PORTIONS, SAID GLOW SWITCH BEING MOUNTED ON A FIRST SIDE OF SAID INSULATING PLATE SO THAT SAID FIRST PORTION LIES JUXTAPOSED SAID APERTURE AND SAID SECOND PORTION EXTENDS THROUGH SAID APERTURE, (D) ELECTRICALLY CONDUCTIVE, THERMALLY SENSITIVE MEANS DISPOSED ON A SECOND SIDE OF SAID INSULATING PLATE HAVING AN END PORTION MOUNTED TO SAID SECOND HOUSING PORTION IN DIRECT ELECTRICAL AND THERMAL CONDUCTIVE CONTACT THEREWITH, AND (E) MEANS MOUNTED ON SAID INSULATING PLATE FOR COOPERATING WITH SAID ELECTRICALLY CONDUCTIVE, THERMALLY SENSITIVE MEANS TO INTERRUPT CONDUCTION OF SAID GLOW SWITCH AND TO PRECLUDE RE-ENERGIZATION OF THE ELECTRIC DISCHARGE DEVICE AFTER ACTUATION OF SAID ELECTRICALLY CONDUCTIVE, THERMALLY SENSITIVE MEANS BY THE HEAT FROM SAID GLOW SWITCH. 